1. Field of the Invention
The present invention generally relates to an electro photographic image forming apparatus such as a copier, a printer, a facsimile machine, or a multifunction machine capable of at least two of these functions, and more particularly, to an image forming apparatus including a conveyance belt to transport sheets of recording media (e.g., paper sheets, resin sheets, and the like) on which toner images are formed.
2. Discussion of the Background Art
Electro photographic intermediate transfer image forming apparatuses generally includes a conveyance member to transport sheets of recording media, an image forming unit to form multiple different single-color toner images (e.g., yellow, magenta, cyan, and black toner images), and an intermediate transfer belt on which multiple single-color toner images are superimposed one on another. The conveyance member may be a conveyance belt disposed engaging the intermediate transfer belt.
For example, JP-H10-055094-A discloses an image forming apparatus in which the conveyance belt is disposed horizontally and the intermediate transfer belt is disposed vertically. In this image forming apparatus, although yellow, magenta, and cyan images are superimposed one on another on the intermediate transfer belt, a photoconductor on which a black toner image is formed is disposed facing not the intermediate transfer belt but the conveyance belt, so that the black toner image is transferred from the photoconductor directly onto transfer sheets carried on the conveyance belt. This image forming apparatus can reduce required time for multicolor image formation while preventing or alleviating deterioration of image quality as well as scattering of toner, thus preventing image failure.
However, in this image forming apparatus, because the photoconductor for black and the intermediate transfer belt are positioned in contact with a linear portion of the conveyance belt, it is possible that the transfer sheet carried on the conveyance belt may fail to adhere to the conveyance belt fully when not transported smoothly, thus creating tiny gaps between the transfer sheet and the conveyance belt. If tiny gaps are thus created, electrical discharging can occur, which disturbs the toner image formed on the transfer sheet, resulting in substandard images.
In view of the foregoing, the inventors of the present invention recognize that there is a need for image forming apparatuses to prevent creation of tiny gaps between the transfer sheet and the conveyance belt, which known approaches fail to do.